The field of the present invention is air cooling systems within electronic systems. More particularly, the present invention relates to a fan assembly for use in an electronic system with circuit modules.
Electronic systems, such as computers, employing modular construction are common. A typical electronic system includes a plurality of circuit modules mounted within a housing. The circuit modules can be easily inserted or removed for replacement or repair. The modular construction contributes to the compactness of the electronic system.
A plurality of modular integrated circuits or chips are typically mounted on each circuit module of current electronic systems. As large scale integration technology has improved, the circuitry per unit area within a modular integrated circuit has increased dramatically. The number of modular integrated circuits which can be packed on a circuit module has also increased. Unfortunately, this increase in the compactness of electronic circuitry has also resulted in an increase in the heat generated per unit area of the circuitry. Therefore, overheating of the numerous chips on circuit modules has presented a serious problem.
To overcome this problem, most electronic systems employ the use of air cooling systems in conjunction with heat sink devices. Typically, air flow from a fan is directed past heat sink devices which are thermally connected to the circuitry on the circuit boards. An example of such a device is illustrated in U.S. Pat. No. 4,122,508 to Rumbaugh. In the modular circuit board assembly disclosed in U.S. Pat. No. 4,122,508, a blower 30 is located in a side panel of the housing 11. The air flow from the blower 30 is directed past heat sinks 19 which are thermally connected to circuit boards 16.
The fan in current electronic systems is usually remote from most of the circuit modules within the electronic system housing. The modular integrated circuits on the circuit modules most remote from the fan receive the least amount of cooling effect because the cooling air absorbs heat as it passes the circuit modules in closer proximity to the fan. In many electronic systems, this problem is exacerbated because the circuit modules which generate the most heat are often required by the physical constraints of the electronic system to be located most remote from the fan. As a result, heat sinks are used to dissipate heat from the integrated circuits more rapidly than would otherwise be possible. However, heat sinks decrease the compactness of the electronic system and increase the cost and complexity of manufacturing the electronic system.
An additional problem arises from the remoteness of the fan from many of the circuit modules within the electronic system. Due to the nature of some system housings, the circuit modules themselves often block the cooling air flow of the fan from reaching the other circuit modules.
A further problem is that modular electronic systems typically have special compartments within the electronic system for housing the fan, thus contributing to expense in the manufacture of the electronic system. A further problem resulting from such compartments is usage of the limited available space within most electronic systems. The special construction of fan compartments further increases the difficulty of removing the fan for maintenance or replacement.